The Pentagon says there are now about 130,000 troops in the Centcom region which takes in North Africa, the Middle East and Asia - including 9,000 in Afghanistan.
This has risen from about 57,000 at the start of the year. Two large deployments were announced in January � one of 62,000, the other of 37,000.
Many of these have how arrived in the Persian Gulf, others are still en-route and may be boosted by three aircraft carriers heading for, or within reach of, the Gulf.
In mid-February the US also activated about 39,000 reservists, bringing the number of reservists on active duty to more than 150,000.
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